What happened to MAFB water?

  • Published
  • By Capt. Todd Brackett
  • 5th Medical Group
MINOT AIR FORCE BASE, N.D. --  On June 24, flood water from the Mouse River entered a large underground storage tank near the city of Minot Water Treatment Plant through an overflow drain line.

The amount of time that river water flowed into the tank is unknown, but operators estimated it could have been 100,000 gallons or more. It is still not known where the contaminated water went to in the distribution system or if the water was actually unsafe to drink, but the Minot Public Water System and all other systems connected to it were forced to issue a boil water order as a precautionary measure.

To date, all pH, free available chlorine and turbidity measurements have been normal, and no water samples have tested positive for bacteria.

Every day the water treatment plant produces 4.5 to 11 million gallons of water. Why be concerned about 100,000 gallons of river water?

Contrary to the adage 'dilution is the solution to pollution,' contamination does not perfectly dilute in water distribution networks. Contamination tends to travel in slugs through the pipes and may generate hazardous conditions in some areas while not affecting others.

So, what are the health hazards associated with flood water?

Untreated river water may contain many biological hazards, to include viruses, bacteria, and other microorganisms which can cause mild to severe illness. The chlorine added during the water treatment process is very effective at killing most bacteria and destroying viruses.

If chlorinated water can kill most viruses and bacteria, than why do we need to worry about a little untreated river water mixing with millions of gallons of treated water?

Some microorganisms are very resistant to chlorine and have the potential to cause serious illnesses. Also, contamination moving through water systems often does not mix perfectly with treated water. There may not be enough chlorine to kill the bacteria, viruses and other microbes before they reach your tap. Boiling water will kill any remaining threat to your water.

What is Minot AFB doing to ensure that our water is safe?

Following the boil water order issued on June 25, Bioenvironmental Engineering has conducted sampling every four hours at points throughout each of the five loops in our distribution system, as well as from the main line which normally connects us to the city of Minot.

What are we testing in the water?

Free available chlorine, pH, and turbidity are collected from each sample site. While none of these parameters alone can prove that a biological hazard is present in our water, they each can be collected quickly and provide indications that a biological hazard may be present.

Below is a brief description of what each test means:

pH: pH must be kept constant in order for chlorine to be most effective against microbes.

Free Available Chlorine: Chlorine is added to the water in the treatment process and as it travels through the pipes some of it is used to kill bacteria and other microbes. FAC is the amount of chlorine remaining in the water when it comes out of the tap. Therefore, if there is no chlorine remaining in tap water, this may indicate the presence of contamination.

Turbidity: Turbidity is a fancy word for how cloudy the water is. Think about how clear water is when it comes out of your tap; now contrast this with the flood water which we have seen this past week. If untreated river water were to mix with the drinking water supply, then we might expect turbidity to increase. Obviously people cannot see the microbes that cause illnesses and cloudy water is not necessarily unhealthy, however the impurities that make the water appear cloudy may be associated with these harmful microbes. The sampling equipment will also allow the detection of very small changes in turbidity that are not visible to the naked eye.

Bacterial Testing: Bioenvironmental Engineers are collecting samples every four hours from the Minot AFB water main. Samples are incubated for a period of 24 hours. At the end of the incubation period, we can determine the presence or absence of bacteria.

Bioenvironmental Engineers will continue increased sampling tempos until the city of Minot lifts the boil water order, the water service returns to normal operations, and public confidence in the city water is restored.